Stud welder



May 18, 1943 E. F. NELSON 22317 STUD WELDER firiginal Filed May 31,- 1940 5 Sheets-Sheet 2 May 18, 1943 E. F. NELSON STUD WELDER Original Filed May 31, 1940 3 Sheets-Sheet 5 :EIBE

/96 vol CONTACTOR I Edward/E'M/saw {m h: ATTORNEY Reissue May 18, 1943 .UNITED STATES PATENT OFFICE Z smf fism h Edward 1. Nelson, Vallejo, c m.

OriginalNo. 2,287,818, dated June so, 1942, Serial No. 338,179, May31, 1949. Application in reissue June so, 1942, Serial No. 449,200

23 Claims.

The disclosure of -invention herein embodies improvements over the structures of my prior Patent No. 2,191,494, issued- Feb. 2'7, 1940, for Stud welders, and my prior Patent No. 2,217,964, issued Oct. 15, 1940, for Stud welder.

It isan object of the present invention to provide welding apparatus of the class described in which the duration of the are between the parts to be joined together may be very accurately adjusted and uniformly maintained.

Another object oi the invention is to provide, in welding apparatus of the class described whose operation, to perform a welding cycle, may be butt-welds between; metallic 012- instituted by depressing a manually actuated conscope of the appended claims.

Referring to the drawings:

Figure 1 is a view, partly in side elevation and partly in vertical section, showing the stud welder and its support.

Figure 2 is a horizontal sectional view of a portion of the support. The plane in which the view is taken is indicated by the line 22 of Figure 1.

Figure 3 is a horizontal sectional view of the lower portion of the support and stud welder. The plane in which the view is taken is indicated by the line 3-3 of Figure 1.

Figure 4 is a vertical sectional view taken in a plane passing medially and longitudinally through the stud welder. The various parts of the structure are shown in the positions they occupy just prior to starting the welding cycle to make a weld. An electrical diagram showing the connections between the various current carrying parts of the apparatus is included as a componcnt part of the view.

Figure 5 is a horizontal crosssectional view of a portion of the stud welder. The plane in which were then threaded on to the studs.

the view is taken is indicated by the line 5-4 of Figure 4.

Figure 6 is a view similar to Figure 4 showing the positions or parts of the after institution of and during the welding cycle.

- Figure 'l is a vertical sectional view of the timing unit for variably adjusting the duration of the welding cycle.

In construction work, particularly in shipbuilding, where steel deck plates are overlaid with wooden planking, it hasbeen the custom in the past to first place the planking, drill holes through the planking and the underlying steel plate and then place in these drilled holes suitable bolts for permanently securing the planking to the plate. The placement or removal of such rtaining bolts required the services of two workmen since one had to hold the bolt against tuming from one side 01. the assembled structure while the other workman applied and cinched the nut from the other side of the structure. Such procedure consumed considerable time and seriously slowed down production. In addition to this, only a slight loosening of one or more of the bolt nuts permitted water to seep, through the bolt holes, below deck. In later and'improved construction a series of threaded studs were electrically butt-welded directly to .the deck plates thus eliminating the through bolt holes and the services of the holder-on for securing the holddown bolt against turning. This procedure, however, required that the planldng, after the studs were placed, be properly positioned over'the studs and tapped so as to impress the ends of the studs into the planking, whereupon the latter was removed, bored to provide the stud apertures, and then replaced on the studs. The hold-down nuts This series of operations consumed nearly as much construction time as the older through-bolt system. In my aforementioned prior applications it was pointed out how considerable time could be saved in sheathing steel structures with wood or other covering material by first pro-forming in the covering the desired number of stud apertures, then placing the covering in its ultimate pomtion on the steel structure and and then electrically buttsoured from the view of the operator, that the distance the stud is drawn away from the plate, in creating the welding arc, and the length of time that the arc is permitted to burn, to eflect raising of the opposed surfaces of the stud and plate to fusion temperature, be very accurately and uniiormly maintained for each successive weld if uniformly strong unions are to be had between the studs and plate. In prior devices the welding head, in which the stud forming one electrode of the welding circuit was held, was supported on a stand or tripod which rested on the upper surface of the planking with the stud projecting downwardly into the planking aperture. Suitable stops on guides 'in the welding head permitted the stud, after contacting the deck plate to be drawn upwardly a predetermined distance to establish the arc gap. However, since the thickness of the planking may vary more or less, it will be seen that variations in the arc gap may also occur which may adversely aifect the quality of the resulting weld.

In the welding heads of my prior applications, I disclosed the use of a dashpot in which oil was displaced by a moving piston to time the duration of the welding arc. This arrangement operated satisfactorily and accurately maintained the timing if relatively small diameter studs were being attached to the plate and if sufllcient time elapsed between welds to allow any heat absorbed by the welding head to be dissipated. However, if heavier studs were being handled, thereby necessitating a longer burning of the arc and if the sequence of welds was rapid, in order to maintain maximum production, considerable heat would be transmitted through the metallic parts of the head to the oil in thedashpot cylinder. Upon becoming heated, the viscosity of the oil changed and consequently lessened the duration of the are which adversely affected the.

strength of the weld.

Another undesirable feature inherent in prior stud welding mechanisms is that no provision is made, during intervals when the operator is handling or conditioning the mechanism between welds, for preventing the heavy welding current from being turned on accidentally, should the operator happen to inadvertently depress the starting trigger with which most of these mechanisms are equipped, and seriously burning the operator if his hands are in contact with a current carrying piece of the apparatus.

All of these undesirable features have been overcome in the device of the present invention. First, the welding mechanism may be quickly set for each weld to produce a uniform arc gap regardless of the amount of variation in thickness of the planking; second, the timing of the weld is accomplished by a device remote from the scene of the weld where it will not be affected by heat absorbed by the welding head;' and, third, a safety device. is included in the mechanism which positively prevents turning on of the welding current until the mechanism has been fully conditioned to make the succeeding weld.

In detail, I have shown in Figures 1, 4, and 6,

- a steel deck plate 8 overlying which is wooden planking 9, which is to be secured to the plate 8, having an aperture ll therethrough into which the threaded stud l2, which is to be butt-welded to the upper surface of the deck plate 8 in the position in which it is shown in Figure 4, may be inserted. A suitable shouldered nut, not shown, isadapted to be threadedly engaged with the stud, after the latter has been welded in position, for tying the planking and the deck plate together. The plate 8 forms one electrode of the welding circuit while the stud i2 forms the other electrode thereof and it is the function of mechanism termed the welding head and generally indicated by the numeral IS in Figure 1, to, first, hold the stud, as shown in Figure 4, in contact with the surface of the plate until the weldin current is turned on; secondly, to draw the stud away from the plate, as shown in Figures 1 and 4, to create an arc gap, and, thirdly, after the end of the stud and surface of the plate have been brought to the melting point by the arc flame, to quickly join the melting members so as to effect the union thereof.

During the welding cycle the main portions of the welding head are rigidly supported in a fixed position. This is accomplished by a suitable supporting structure such as that fullydescribed in my application Serial No. 410,793 filed September 13, 1941, comprising a base ll, which rests on the upper surface of the planking 9, having therein an opening l6, through which the stud i2 may be raised and lowered, and an upwardly rising tubular post l'l which is secured, at its lower end, to the base by a screw l8. Telescoping over and slidable axially of the post I1, is a tube I! having thereon a pair of spaced brackets, each comprising a split collar 2i secured to the tube by means of a clamp screw 22 and having extensions 23 whichare attached to the welding head l3 so as to position the latter axially concentric with the base opening [6. A key 24, projecting through a suitable opening formed in and adjacent the lower end of the tube i9 and entering a keyway 26 cut' longitudinally in the periphery of the post i1, serves to prevent relative rotation between the tube and post and thereby to maintain the stud I! in axial concentricity with the base opening [5. The upper end of the tube is extends into a bored recess 21 formed in a hub 28 having a radially projecting grip 29, and the hub is split axially of the recess 21 and provided with apertuted lugs 3i bearing a clamp belt for clamping the tube I! in the recess 21. The grip 29 provides a hand hold for the operator so that he may rais and lower the welding head with respect to the base i4.

Means is provided for securing the welding head in a selected elevated position. Secured at its upper end in the recess 21, by the clamp bolt 32, and positioned within the tube I9, is a collet sleeve 33 which extends downwardly in axial'concentricity with the tube l9, terminates adjacent the lower end of the latter, and telescopes within the post IT. The lower end of the collet sleeve is provided with a plurality of circumferentially spaced, axially extending, slots 3, and with a tapered countersink 35 forming a continuation of the internal bore 31 of the sleeve. c0nstruction provides a plurality of radially flexible fingers at the lower end of the collet sleeve. Positioned concentrically within the collet sleeve is a control rod 38 secured to the lower threaded end 39 of which is a. frusto-conical plug 4| complementary with and engaged in the tapered countersink 36 of the collet sleeve. The upper end 42 of the control rod passes slidably through a central aperture formed in a washer 43 which rests, in a fixed position spaced from the upper end of the collet sleeve, against a shoulder formed within the bore of the sleeve. A nut 44 is threaded on the extreme upper end of the, control rod; and interposed between the nut 14 and the washer l, is expansion spring 46. The spring 46 is for the purpose or urging the control rod 38 upwardly in a direction axially of the collet sleeve 33 so as to draw the plug 4| into the countersink 88 thereby radially urging the flexible flngers into tight frictional engagement with the inner periphery of the post [1. This looks the fraction of an inch and chosen to produce the desired arc flame depending upon the amount of welding current available. It will be seen that if the distance between the upper surfaces of the deck plate I and-the overlying planking 8 is uniformly the same in'each aperture H in which a movable tube I9 and the post l1 against relative longitudinal displacement and also holds the welding head firmly in the desired elevated position. In the event that a weldinghead or considerable weight is being used, the peripheral surfaces of the fingers contacting the post II may be knurled so as to bite into the surface of the post and thereby obtain maximum grip between ,the engaged parts.

Means is provided for releasing the connected post I! and tube i8, to permit raising and lowertubular members are provided with aligned aperi tures which form, as is best shown in Figure 2, an. opening 48 through which passes a release lever 49. A pin 5 l having its Opposite ends seated in holes. drilled into the tube l9 and filler 41.

extends transversely across the opening 48 and through a journal hole bored in the release lever so that the latter is pivotally mounted on the pin.

The inner end of the release lever is bifurcated to provide a. pair of fingers 52 which bear against a washer 53 secured to the control rod 38, and the wardly so as to move the plug 4| out of the couni tersink 35 thereby releasing the radial pressure .of the collet fingers against the inner wall of th post l1. With the base maintained in contact with the surface of the planking 9, the tube I9 and the various parts. including the welding head.

carried thereby may be shifted longitudinally of the post I! to any desired position. Release of the lever extension 54 will again set the friction lock to secure the welding head in fixed relation to the base I4. An axially e Dansible spring 56,

positioned within the tube l9, and interposed between the ends of the post I1 and the filler tube 41, respectively, serves, when the friction lock is released, to urge the tube l9 and its connected parts upwardly thereby partially counterbalancing the weight of the welding head I3.

As was stated above, a uniform arc gap shou d be maintained in successive welds if each weld is to possess the maximum of strength. {is will be explained in detail later, the mechanism of the welding head is pre-set so that, as shown in Figure 4, the lower end of the stud l2 rests on the upper surface of the deck plate 8. When the welding current is turned on, action takes place within the welding head, and while the latter 1s held rigidly fixed with relation to the deck plate, which moves the stud I! to a position elevated above the deck plate, as shown in Figure 1, to create the arc gap between the stud and plate. The length of this are gap is usually only a small g of the apertures will not be alike.

stud is to be placed, the welding of a large number of studs may be carried forward in the knowledge that the arc gap of each successive weld will be the same 'as that of the previous welds. However, due to variations in thickness in the planking 9 and the possibility of raised seams,

protuberances or depressions in the surface of the deck plate 8 happening to coincide with one or more of the apertures II, the depths of all Using previously known equipment, work was seriously retarded by the requirement that the workman, before making each weld, measures the depth of each hole and set the welding head support to provide the desired are gap. With the apparatus of my invention, it is only necessary, after the welding head has been conditioned, or "cocked, as shown in Figure 4, to place the base l4 in position on the planking 9 ,over the aperture II, and

, release the friction lock between the postl1 and tube l9 so as to allow the stud I2 to descend into the aperture ll until it just touches the surface of the deck plate. The lock may be then re-engaged since the stud is now positioned to provide the correct length ofarc gap when it is drawn away from the plate bythe mechanism within the welding head. It will be therefore seen that a workman may quickly set the apparatus for each individual hole in which a stud is to b mounted without appreciably cutting down his Production speed. a

The welding .head comprises a preferably cast metallic casing 51, having at its lower end a plurality, preferably three, of bosses 58 each being provided with threaded sockets 59 which receive screws 60 for securing the lower bracket extension 23 to the'casing 51. The threaded sockets 59 also may be used, when the welding head is being employed without its supporting structure shown in Figure l, to receive the threaded ends of coaxial rods whose lower ends may rest against the planking so as to form a tripod for supporting the welding head in axially vertical position. Such a support may be employed when the welding head is being used in cramped quarters in which there is not sufficient headroom for proper operation of the supporting structure of Figure 1.

Means is provided for supporting the stud I! so that it may be moved; independently of the movement thereof permitted by the adjustable supporting structure described above, along a path away from and towardthe surface of the deck plate 8. A chuck BI is provided, the lower end of which is centrallybored to form a socket, which receives the upper end of the stud l2, and is provided with longitudinally extending slots 62 which form, at the lower end of the chuck, a plurality of flexible fingers B3 gripping the stud and frictionally holding the latter in the chuck socket. The opposite end of the chuck is provided with a. threaded bore 64 in which the correspondingly threaded shank 66 of a plug 61 is engaged. Surrounding the periphery of theplug 61 is an insulating sleeve 68 having a peripheral flange 89 thereon. An insulating disk H overlies the end of the plug 61, adjacent the insulating sleeve 88 and is provided with an annular skirt I2 which overlie-s a retaining flange 13 on the plug. Surrounding the insulating sleeve 68 and disk H is a is pressed one end of a tubular skirt I81.

cap I4 havingan annular lip' 18 engaging the shoulder of the flange 89 and which is internally threaded and engaged with a correspondingly threaded flange 11 formed at one end of a tubular ram 18 so as vtoclamp the plug 81 to the ram. The provision of the diskll and the sleeve 88 electrically insulates the stud '2 and its supporting chuck from the ram" and the remainder of the mechanism which will presently be described.

The ram 18 is mounted so as to freely slide axially of and within a stationary tube 19, the latter being provided with a fixed key 8| which operates in a slot 82 formed in .the ram so that motion of the ram is confined to axial directions, the key 8| serving to prevent any relative rotational movement between the ram and the tube. The end of the tube 19 adjacent the flange 11 of the ram is spaced from the latter a distance corresponding to the length of arc gap desired so to engage the threads in the bore of a hub 88 formed at the end of the casing 51. This mounts the tube in fixed relation to and concentric with the casing within the bore 81 thereof.

A circular disk 88, best shown in Figure 5, is provided with a pair of concentric arcuate apertures 89 and with bridge portions 9| passing through theslots 84 of the tube 19, the portions 92 of the tube between the slots passing through the diskapertures 89. The disk is thus mounted concentrically with the tube and is free to be moved axially thereof in the slots 84. The disk is provided with a central countersunk aperture which receives the conical head 93 of a bolt 94 which extends concentrically oi the ram 18 toward the lower or chuckend thereof. A spacer tube 98, on the bolt 94, passesslidably through a central aperture formed in a wall 91 formed in the ram I8 intermediate the ends thereof and a coil spring 98, concentric with the bolt, is interposed between the wall 91 and the disk 88. A relatively larger tube 89 is also carried by the bolt 94 and this latter tube and the spacer tube 98 are secured in place by means of a nut I8I and washer I82 secured to the extreme lower end of the bolt.. A coil spring I83 concentric with the bolt has its respective ends engaged with the ram wall 91 and the washer I82. The shoulder I84 provided between the smaller and larger tubes 98 and 99v acts as a stop against which the ram wall 91 may impinge to limitdownward movement of the ram. The outer periphery of the disk'88 is provided with a circular shoulder I88, onto which A sleeve I88 is slidably mounted on the tube 19 and has an end flange I89 engaging the disk 88, and a similar sleeve I I I is slidably mounted on the lower end of the tube 19 and has a peripheral flange I I2 against which is positioned an annular collar I I3 peripherally shouldered to receive one end of a tubular skirt II4 projecting into the casing bore 81. The sleeve I I I, collar H3 and skirt II4 are all secured together as ,a unit. Surrounding the sleeves I88 and III and extending between the flange I89 and collar II3 is an axially expansive coil spring H8. The spring I I8 is normally held under compression and serves as the actuating member for forcibly. moving the stud I2 successively away from and toward the surface of the deck plate 8.

Means is provided for releasing one end of the coil spring 8 so as to move the stud I2 away from the deck plate 8 so as to create the arc gap therebetween. Positioned adjacent the lower edge of an opening II1, formed in the side wall of the casing 51, is a pair of spaced lugs III bearing a pivot pin I I9 upon which is journaled a latch lever I2I having a dog I22 thereon which is engaged with the upper surface of the disk 88. A relatively longer pair of lugs I23 are provided, spaced from the lugs II8, which carry a pivot pin I24 and a stop pin I28 spaced from the pivot pin I24. On the pivot pin I24 is pivotally mounted a trigger I 21 and one section I28 of a hinged link; the other section I29 of the link being attached by means of a pivot pin I3I to the latch lever I2I. A pivot pin I32 connects the two sections I28 and I29 of the hinged link. A torsion spring I38 urges the link section I28 against the stop pin I28. The trigger I21 is provided with an integral extension I33 carrying a trip pin I34 which overlies an edge of the section. I28 of the hinged link. Plvotally mounted on a pivot pin I38, which is carried by a pair of lugs I31 positioned adjacent the lower end of the casing 51,

is a latch lever I38 having a dog I39 which engages the lower surface of the collar H3. The spring IIG, which is under compression when the welding head is ready for use, is therefore confined against longitudinal expansion by the latch dogs I22 and I38. Viewing the structure of Figure 4, when the operator pulls the trigger I21, the trip pin I34 will contact and swing the link section I28 about the letters pivot so that the center of the hinge pivot I32 will be moved out of the plane passing through the axes of all of the pivots thereby causing the hinged link to buckle and permitting the latch lever dog I22 to release its engagement with the disk 88. This=permits the disk 88 to move upwardly under the influence of the expanding spring II8 until the disk engages a rubber bumper I4I seated adjacent the bottom of the casing bore 81. Movement of the disk 88 will cause a corresponding movement upwardly of the bolt 94 and consequently the ram 18 will be moved until the upper face of the flange 11 impinges against the lower end of the tube 19. This raises the stud I2, as shown in Figure 6, to a position elevated above the deck plate 8 so that the arc gap 83 is created between the deck plate and the lowerend of the stud.

Means is provided for conducting welding current to the stud I2 so as to create an electric arc between the stud and deck plate. The threaded end of the tube 19 extends upwardly beyond the upper end of the casing 51 and is engaged with one endof a tubular steel shell I42. On the shell I42 is mounted the split collar I43 formed integrally with a hollow pistol-grip handle I44; a screw I48 passing through apertured lugs I41 formed on the collar I43 serving to clamp the collar securely to the shell I42. The outer end of the handle I44 is provided with a pair of openings through one of which passes a welding current cable I48 and through the other of which passes a control current cable I49. After entering the handle I44 the cable I48 emerges from the side thereof through a tubular boss I5I, as shown in Figure 1, is then formed with a loop I52 and is provided .at its end with a spade connector I53- whose apertured end is secured on the shank 88 between the chuck 8| and the plug 81. The other end of the cable I48 is connected to one terminal I64 of an electro-magnetic contactor I66, the other terminal I61 oi the contactor being connected to one end of a conductor I69 which connects with an output terminal of a direct current welding current generator I59. A conductor 5 solenoid I62 drives an armature I63 in the contactor I56 to move the movable contact I64 into engagement with the fixed contact I66 so as to make or break the circuit between the conductors I46 and I59.

Positioned within the handle in and electrically insulated therefrom by insulating blocks I61 and a flexible insulating strip I68, which are mounted on the handle by screws I69, is a pair of flexible metallic switch blades HI and I12 which, in their normal positions of rest as shown in Figure 4, are spaced apart at their free ends. The upper switch blade I1I is provided with an extension I13, projecting beyond the contacts I 14 to which is attached, by rivets I16, a strip of insulating material I11. A push button I18, slidably mounted in an apertured boss I 19, positioned adjacent the end of the switch blade I12, has one end thereof positioned in contact with the insulating strip I69 below the said end of the switch blade I12 and the other end thereof in contact with the trigger I21 at a point thereon spaced from the trigger pivot pin I24.

Within the shell I 42, and positioned adjacent the bottom thereof, is an annular iron pole piece I8I which is centrally bored to receive one end of ::5

the upper end thereof, a flange I81 engageabie with the upper surface of the disk I93 so that the downward movement of the armature I94 may notexceed a given limit and a coil spring I69, having its lower end engaged with the armature and its upper end engaging a cap I99 which is mounted by means of threads I9I, on the upper end of the sleeve I42, serves to urge the armature toward its lower limit of travel. A guide pin I 92,

' secured in the cap I89 and extending into the spring I99 for substantially half of its length 55 prevents lateral buckling of the spring when the latter is compressed; and a vent opening I93 permits the escape of compressed air from the interior of the cap when the armature is moved upwardly. A solenoid coil I94, placed'within the 0 shell I42, concentric with the armature I 84 serves to create magnetic flux in the magnetic circuit to move the armature upwardly against the pressure oi the spring I88.

. A timer I96 is provided which, together with the magnetic contactor 156, may be placed in a position remote from the welding head such as, for instance, on the usual portable hand truck which carries the welding generator I59. The timer comprises a pair of relay contacts I91 which may be bridged by a movable contactor-l99'carried on an armature I99 which is actuated by a solenoid coil 29I. As is shown in Figure 7, the timer includes a variable dashpot which controls the welding cycle. The dashpot, which may be one The disk I83, shell I42 and polel of several well-known makes obtainable in the open market, comprises a housing 292 having in opposite sides thereof recesses 293 and 294 which are each covered by flexible diaphragms 296 and 291 to provide a pair of separate chambers 298 and'299 in the housing. The diaphragms are secured to the housing by suitable pressure plates 2 and screws 2I2. In the housing wall 2I3 separating the two chambers 299 and 299, is one or more by-pass openings 2I4,' normally closed by a spring-pressed check valve 2I6 which opens downwardly into the chamber 299, and a bleeder passage 2I1 into which extends a tapered blocking valve 2I8 carried on athreaded stem 2I9 tapped into the housing. The outer end of the stem 2I9 carries a dial 229 upon which suitable graduations indicating desired time settings are carried. ,The lower end of the armature I99,

or a rod extension of the armature, is threadedly' engaged in a hub 22 I secured, together with clamp washer 222, to the upper. diaphragm 296. The weight of the armature I99 normally maintains the-upper diaphragm 296 in depressed condition so that substantially all of the air in the upper chamber 298 is forced through the by-pass opening 2 and past the check valve 2 l6 into the lower chamber 299.. When the solenoid 29I is energized it will urge the armature I99 upwardly thereby creating a reduced pressure in the upper chamber 299 and causing the air in the lower chamber to flow through the bleeder passage 2I1 past the blocking valve 2I8 into the upper chamber. This creates resistance to the upward movement of the armature depending upon the rate at which the air is allowed to flow past the blocking valve.

Control current input leads 223', which are connected to a source of volt alternating current, are provided, one of which is connected to the upper end of each solenoid coil I62 and 2M and also to one of the timer contacts I91. The other lead 223 is connected by a conductor 224 to the upper switch blade I1I, in the handle 4, and also to one end of the solenoid coil I94. The other conductor 226 from the coil I94 is run directly to the other timer contact I91. The lower switch blade I12 is connected by a conductor 221 to the lower ends of each of the solenoid coils I62 and 29I.

When the trigger I21 is pulled by the operator, so as to release the latch lever I2I and permit the spring II6 to raise the stud I2 to create the arc gap 83, the push button I18 is simultaneously moved upwardly, as shown in Figure 6, to move the lower switch blade I12 upwardly toward the other switch blade "I so as to engage the contacts I14. This closes the circuits to each of the solenoid coils I62 and MI, causing the former to engage the contacts I64 and IE6 of the welding current contactor I56 so as to create the arc flame between the stud I2 and deck plate 9, and

causing the latter to start the timer armature I99 in its upward movement. As soon as the contactor'l98 of the timer reaches and bridges the contacts I91, current will flow into the solenoid coil I94 which will then cause the armature I94 to move upwardly against the pressure of the spring I88.

Means is provided, which is actuated upon movement of the armature I84, for releasing the lower end of the spring I I6 50 as to plunge the end of the stud I2, which will now have been brought by the arc flame to a temperature very close to the melting point of the stud metal, into the molten metal of the arc crater in the deck plate the welding current. now, separated a distance greater-than the maxi thereby effecting the weld between the parts to be joined. Mounted on the lower end of the armature I33, by a screw 228 which is tapped into the end of the armature, is a trip bar 229 which extends through the casing opening I I1 and contacts, during upward movement of the armature, the end of one arm 23I of a bell crank which is pivotally mounted on the trigger pivot pin I24 and which has its other arm 232 extending downwardly toward the lower end of the welding head. A rod 233 engaged at its respective ends in apertures formed in. the bell crank arm 232 and in the latch lever B3 to provide pivots. 234 and 236 connects these parts for movement together. channel-shaped guard 231 secured by suitable screws to the casing 51 protects the latch levers and their associated parts against exposure or damage. As soon as the trip bar 223 raises the arm 23I, the planar alignment of the pivots I2l'234-236 will be disturbed and will permit the arm 232 to swing; to its position shown by the .sembly thereby returning the end of the stud I2 into engagement with the deck plate 8. Simultaneously with this action, the arm 23 I in moving upwardly, contacts the insulating member I11 of the upper switch blade, to the position indicated by the dot and dash'lines, to cause the con tacts I14 to separate This immediatel deeiiergizes the solenoid coil I82 and opens the contactor contacts I and IE6 thereby shutting off Since the contacts I14 are mum movement of the push button I13, the welding current may not be deliberatelyor accidental- ,ly turned on by pressure against the trigger I21 until the welding head is again conditioned to make the succeeding weld. This safety feature prevents theloperator from receiving severe accidental burns or shocks. After the weld is completed the welding head is lifted so as to pull the stud from the chuck. The resistance offered by the stud to being separated from the chuck is sufiicient to cause the plunger and its associated ception of a-possible adjustment of the support should the new hole, in which the stud is to be welded, happen to vary in depth from the preceding one.

I claim:

1. In combination, an electric welding circuit including first and second metallic members to be welded together and forming the respective electrodes of said welding circuit, a welding head including a movable ram carrying said first metal-. lic member, a, support, for engaging a surface adjacent said second metallic member, carrying said welding head and adjustably extensible to primarily move said welding head, ram and first metallic member bodily toward or from said second metallic member, unitary confined pressure 75 electrodes of said welding circuit, a welding head 7 means in said welding head and operatively connected with said ram for successively secondarily moving said ram and the first metallic member carried thereby into spaced relation with said second metallic member, to establish an electric are between the said metallic members, and then into contiguous relation to join said metallic members, means for releasing said confined pressure means to move the ram and first metallic member into spaced relation with the second metallic member, and separate means for releasing said confined pressure means to move the ram and first metallic member toward said second metallic member,

2. In combination, an electric welding circuit including first and second metallic members to be welded together and forming the respective electrodes of said welding circuit, a welding head including a movable ram carrying said first metallic member,- a support, for engaging a surface adjacent said second metallic member, carrying said welding head and adjustably extensible to primarily move said welding head, ram and first metallic member bodily toward or from said second metallic member, unitary confined pressure means in said welding head and operatively connected with said ram for successively secondarily moving said ram and the first metallic member carried thereby into spaced relation with said second metallic member, to establish an electric arc between the said metallic members, and then into contiguous relation to join said metallic members, manually operable means for releasing said confined pressure means to move the arm and first metallic member into spaced relation with the second metallic member, means operative at the end of a predetermined interval or time after operation of said manually operable releasing means for releasing said confined pressure means to move the ram and first metallic member toward said second metallic member, and means situated remote from said welding head for adjustably varying said interval of time.

3. In combination, an electric welding circuit including first and second metallic members to be welded together and forming the respective electrodes of said-welding circuit, a welding'head including a movable ram carrying said first metallic member, a support, for engaging a surface adjacent said second metallic member, carrying at the end of a predetermined interval of time after operation of said manually operable releasing means for releasing the other end of said spring to move the ram and first metallic member in an opposite direction toward said'sece ond metallic member, and means situated remote from said welding ,head for actuating said electro-magnetic spring releasing means.

4. In combination, an electric welding circuit including first and second metallicmembers to be welded together and forming the respective 'ing an electric circuit to said coil during operaincluding a movable arm carrying said first metallic member, a support, for engaging a surface adjacent said second metallic member, carrying said welding head and adiu'stably extensible to primarily move said welding head, ram and first metallic member bodily toward or from said second metallic member, a unitary spring mounted in said welding head' and engaged with and expansible to move said ram alternatelyin opposite directions, first and second latch levers pivotally mounted on said welding head and releasably engaging opposite ends of said spring for confining said spring under compression, a manually operable trigger pivotally mounted on said welding head and operatively connected with and to move said first latch lever to release one end of said spring so as to move the ram and the first metallic member into spaced relation with the second metallic member, an electro-magnetically actuated armature movably mounted in said welding head, a bell crank pivotally mounted On said welding head operatlvely connected with and to move said second latch lever to release the other end of said spring so as to move the ram and first metallic member toward the second metallic member, saidbell crank having an arm extending into the path of movement of, and to be moved by, said armature, and means situated remote from said welding head operatively connected with and to move said armature.

5. In combination, an electric welding circuit including an electro-magnetically controlled contactor and first and second metallic members to be welded together and forming the respective electrodes of said welding circuit, an electromagnetically actuated variable, interval timer, a welding head including a movable ram carrying said first metallic member, a support, for engaging a surface adjacent said second metallic member, carrying said welding head and adjustably extensible to primarily move said welding head, ram and first metallic member bodily toward or from said second metallic member, a unitary spring mounted in said welding head and engaged with and expansible to move said ram alternately in opposite directions, first and second latch levers pivotally mounted on saidwelding head and releasably engaging opposite ends of said spring for confining said spring under compression, a manually operable trigger pivotally mounted on said welding head and operatively connected with and to move said first latch lever to release one end of said spring so as to move the ram and the first metallic member into spaced relation with the second metallic member, a control switch mounted on said welding head and connected with and to be closed by said trigger upon movement of the latter, said control switch being included in control circuits for energizing said contactor to close the welding circuit and for starting said interval timer, a bell crank pivotally mounted on said welding head operatively connected with and to move said second latch lever to release the opposite end of said spring so as to move the ram and first metallic member into engagement with the second metallic member, said bell crank having an arm extending therefrom, a solenoid coil in said welding head, an armature within and movable by the coil upon excitation of the latter, said armature having an extension thereof engageable with said bell crankextem sion so as to connect the armature and bell crank for movement together, and a switch in said timer in circuit with said solenoid coil for 0105- tion of said timer. 1

6. In combination, an electric welding circuit including an electro-magnetically controlled 'contactor and first and second metallic members to be welded together and forming the respective electrodes of said welding circuit, an electromagnetically actuated variable interval timer, a welding head including a movable ram carrying said first metallic member, a support, for n aging a surface adjacent said second metallic member, carrying said welding head and adjustably extensible to primarily move said welding head, ram and first metallic member bodily toward or from said second metallic member, a F8 7 spring mounted in said welding head and engaged with and expanslble to move said ram alternately in opposite directions, first and second latch levers pivotally mounted on said welding head and releasably engaging opposite ends of said spring for confining said spring underv compression, a manually operable trigger pivotally mounted on said welding head and operatively connected with and to move said first latch lever to release one end of said spring was to move the ram and the first metallic member into spaced relation with the second metallic member, a control switch mounted on said welding head and connected with and to be closed by said trigger upon movement of the latter, said control switch having a pair of fiexible contact arms one of which has an extension, said control switch being included in control circuits for energizing said contactor to close the welding circuit and for starting the operation of said interval timer, a solenoid coil in said welding head, an armature within and movable by the coil upon excitation of the latter, said armature having an extension thereon, a switch in said timer in circuit with said solenoid coil for closing an electric circuit to said coil during operation of said timer, a bell crank pivotally mounted on said welding head operatively connected with and to move said second latch lever to release the opposite end of said spring so as to move the ram and first metallic member toward and into engagement with the second metallic member, said bell crank having an arm extending,

therefrom into the path of movement of said armature extension so as to be engaged and moved by said extension upon movement of the armature, and said bell crank arm being movable, by and upon release of said opposite end of the spring, into engagement with said control switch extension to open said control switch.

7. In combination, a welding head for carrying a first metallic member to be welded to a second metallic member, means for positioning said welding head relative to said second metallic member, a single self-propelling element in said welding head for moving said first metallic member in a cycle from and toward said second metallic member, and means positioned said first metallic member toward said second metallic member, powered release mechanism in said welding head for controlling movement of said moving element for the first metallic mem her, a timer remote from said welding head for instituting power pulses at substantially identically spaced intervals of time after movements of said first metallic member away from said second metallic member, and means for conducting said power pulses from said timer to 'said' powered release means.

9. In combination a welding head for carrying a first metallic'member to be welded to a second metallic member, means for positioning said welding head relative to said second metall'.c member, and a single self-propelling ele ment in said welding head for moving said first metallic member in a cycle fromv and toward said second metallic member.

10. In a welding apparatus, a casing, a ram slidably mounted in said casing, a spring for moving the ram axially in either direction, a pair of latches for restraining the action of the spring, means for releasing one oi the latches to permit the spring to move the ram in one direction, and

time controlled means remote from the casing 'means for closing a welding circuit, means for releasing the other latch to permit the spring to move the ram in the other direction, time controlledmeans remote from the casing and initialed by the first named releasing means for operat ng the last named releasing means, and means acting in time with said last named releasing means for opening the welding circuit.

12. In a welding apparatus, a casing, a ram slidably mounted in said casing, a spring for moving the ram axially in either direction, a pair of latches for restraining the action of the spring, means for releasing one of the" latches to permit the spring to move the ram in one direction, means for releasing the other latch to permit the spring to move the ram in the other direction, and means acting in time with movements of the ram for closing and opening a welding circuit.

13. In a welding apparatus, a casing, a ram slidably mounted in said casing, a spring for moving the ram axially in either direction, a. pair of latches for restraining the action of the spring, means for releasing one of the latches to permit the spring to move the ram in one directon, means acting in time with the releasing means for closing a welding circuit, means for releasing the other latch to permit the spring to move the ram in the other direction, time controlled means acting in time with the first named I 22,317 after an interval of time, for further moving restraining movement of the spring means, manually operated means for releasing one of the latches to permit the spring means to move the ram in one direction, a solenoid and circuit for and means acting in time with movements of the ram for closing and opening a welding circuit.

15. In a welding apparatus, a casing, a ram axially slidable in said casing, spring means for moving the ram in either direction, latches for restraining movement of the spring means, manually operated means for releasing one of the latches to permit the spring means to move the ram in one direction, a solenoid and circuit for releasing the other latch to permit the spring means to move the ram in the other direction, and time controlled means initiated by said manually operated means for closing the solenoid circuit.

16. In a welding apparatus, a casing, a stud I within the casing, a ram slidable on the stud,

a pair of spaced push rings slidable on the stud and operatlvely connected to move the ram, a spring compressed between the push rings, a latch associated with each push ring for controlling its spring pressed movement, manually operated means for releasing one of the latches, a solenoid and circuit for releasing the other latch, and means timed from the operation of the manually operated releasing means for closing the solenoid circuit.

17. In a welding apparatus, a casing, a stud within the casing, a ram slidable on the stud, a

pair of spaced push rings slidable on the stud.

and operativeiy'connected to move the ram, a spring compressed between the push rings, a latch associated with each push ring for controlling its spring pressed movement, manually operated means for releasing one of the latches, means for releasing the other latch, and time controlled means remote from the casing and acting in time with the manually operated re leasing means for operating said other latch releasing means. I

18. In anapparatus for electrically welding a stud to a plate, a casing, a ram slidably mounted in said casing and having means thereon for holding the stud against the plate, a pair of I spaced push rings slidable in the casing and releasing means for operating the last named 14. In a welding apparatus, a casing, a ram axially slidable in said casing, spring means for moving the ram in either direction, latches for operatively connected to move the ram, a spring compressed between the push rings, a pair of latches for restraining the action of the spring, a welding circuit arranged for connection through stud and plate, manually operated means for releasing one of the latches to permit the ram to raise the stud from the plate, time controlled means acting in time with said manually operated releasing means for releasing the other latch to permit the ram to engage the stud with the plate, and means acting in time with movements of the ram for closing the welding circuit before the stud is raised from the plate and opening the welding circuit before the stud is engaged with the plate.

19. In an apparatus for electricallywelding a stud to a plate, a casing, a ram slidably mounted in said casing and having means thereon for holding the stud against the plate, a pair of spaced push rings slidable in the casing and operatively connected to move the ram, a spring compressed latches for restraining the action of the spring. I

between the push rings, a latch associated with each push ring for controlling its spring pressed movement, a welding circuit arrangedfor connection through stud and plate, manually operated means for releasing one of the latches to permit the ram to raise the stud from the plate, time controlled means "acting in time with said manually operated releasing means for releasing the other latch to permit the ram to engage the connected to move the ram, a spring compressed between the push rings, a latch associated with each push ring for controlling its spring pressed movement, a welding circuit arranged for connection through stud and plate, manually operated means for releasing one of the latches to per-- mit the ram to raise the stud from the plate, a

solenoid and circuit forreleasing the other latch, and means timed from the operation of the manually operated' releasing means for closing the solenoid circuit to permit the ram to engage the stud with the plate, and time controlled means initiated by the manually operated means for closing and opening the welding circuit in correlation with the movements of the ram.

21. In an apparatus for electrically welding a stud to a plate, a casing having a foot thereon for supporting the apparatus, a ram slidably mounted in said casing and having means thereon for holding the stud "against the plate, means for adjusting the foot on the casing to vary the position of the ram with relation to the plate, a spring for moving the ram ineither direction, a pair of means for releasing one of the latches to permit the spring to move the ram away from the plate, and time controlled means initiated by the releasing means for releasing the other latch to permit the spring to move the ram toward the plate.

22. In an apparatus for electrically weldinga stud'to a plate,-a casing, a ram slidably mounted in said casing and having means thereon for holding. the stud against the plate, a spring for moving the ram in either direction, a pair of latches for restraining the action of the spring, a welding circuit arranged for connection through stud and plate, manually operated means for releasing one of the latches to permit the springto move the ram to raise the stud from the plate, time controlled means acting in time with said manually operated releasing means for releasing the other latch to permit the spring to move the ram to seat the stud on the plate, means initiated by said manually operated means for closing and opening the welding circuit in correlation with the movements of the ram, and means for preventing closing of the welding circuit when the last named latch is in released position.

23. In a welding apparatus for Welding a stud to a plate through an apertured covering, a welding head including means for holding the stud, a support releasably connected to the welding head and including a hand grip and also a foot on which the apparatus rests upon the covering, and manually operable release means adjacent the hand grip for adapting the welding head and the support to correct their relative positions under the pull of gravity when the stud in the welding head and the support are placed-on said plate and covering.

EDWARD F. NELSON. 

